Interactive exercise apparatus

ABSTRACT

An interactive exercise apparatus engages a user&#39;s mind and body. The apparatus comprises an exercise mechanism and a steering mechanism for manipulation by the user to achieve exercise and to indicate a direction of motion. The exercise mechanism can be, for example, the steps of a stair climbing simulator or the pedals of a bicycle, preferably a recumbent bicycle. A simulated environment (e.g., an interactive simulated three-dimensional environment or an interactive simulated three-dimensional fluid environment) is generated by a computer and displayed on a display system for the user. The user manipulates. the exercise mechanism and the steering mechanism to travel substantially unrestricted throughout the simulated environment. The computer controls the exercise mechanism and monitors the exercise mechanism and the steering mechanism to determine user position in the simulated environment. The display provides a visual display of the user&#39;s position in the simulated environment. A plurality of the interactive exercise apparatus can be networked together to allow group participation in the simulated environment.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part of U.S. patent application Ser. No.08/189,896, U.S. Pat. No. 5,466,200, filed on Feb. 1, 1994 which is acontinuation-in-part of U.S. patent application Ser. No. 08/012,305filed on Feb. 2, 1993 which is now abandoned. U.S. patent applicationSer. No. 08/012,305 was abandoned in favor of U.S. patent applicationSer. No. 08/375,166, U.S. Pat. No. 5,462,503, filed on Jan. 18, 1995which is a continuation of abandoned U.S. patent application Ser. No.08/012,305.

FIELD OF THE INVENTION

This invention relates generally to exercise equipment and networkableexercise equipment.

BACKGROUND OF THE INVENTION

It is known that physical fitness is of prime importance to many people.Historically, people have been able to maintain an acceptable level offitness simply due to their everyday lives. As lifestyles have becomeprogressively more sedentary, people have been forced to seek exercisein other ways.

A portion of society keeps in shape by participating in group exerciseevents such as tennis, hockey, or basketball games. Such games are formsof "fun exercise" in that participants often take part in such eventsbecause they simply enjoy the games or the competition and not solelyfor the purpose of fitness. However, it is often difficult to coordinatethe people and facilities required for many recreational and teamsports. Individual sports such as bicycling, running, and swimming areviable alternatives in that they allow for flexible schedules. Some ofthe disadvantages to these sports are that they are location and weatherdependent.

A large segment of society finds it easier and more convenient to go tohealth clubs or to use home exercise equipment to exercise. Health clubshave extended hours and a wide range of fitness equipment that allowsworkout schedules to be flexible and workouts to be quick. Currentexercise equipment unfortunately makes working out a chore that istolerated due to the importance of cardiovascular (aerobic) fitness.

Exercise equipment generally falls into two categories: strength andaerobic. Strength equipment includes traditional free weights as well asmachines on which the weight is not directly attached to the liftingbars. The user lifts the weights in different ways to strengthen variousmuscle groups. Aerobic machines improve the user's cardiovascular systemand tone muscles rather than building muscles and strength. Aerobicequipment includes exercise cycles, treadmills, and stair climbers.Typically, the required speed or resistance can be varied during aworkout. A control panel equipped with a set of light emitting diodes(LEDs) may be provided to depict the routine as a histogram. An averageworkout lasts approximately 20 minutes. Biomechanical feedback such ascalories burned may also be displayed on the control panel.

Most conventional ways of exercising generally are not fun or engaging.A need exists for exercise equipment which makes workouts more enjoyableand fun and which entices more people to exercise.

SUMMARY OF THE INVENTION

An object of the present invention is to provide exercise equipmentwhich makes exercise (e.g., aerobic exercise) less boring and more fun.To accomplish this, the present invention utilizes computer-generatedgraphics, interactive software, a mechanism for aerobic exercise,steering controls, and a display system to provide exercise equipmentwhich is engaging and fun and which allows competition. The graphics,interactive software, and display engage a user mentally while theexercise and steering mechanisms engage the user physically. As such, aworkout with the exercise equipment of the present invention can be asexciting as participating in team sports but with health club or homeconvenience.

The invention also involves the interconnection of two or more exercisemachines via computer networking or, more generally, via any type ofanalog and/or digital communication system such that the users of theexercise machines can interact with each other as teammates orcompetitors in a variety of athletic events including basketball games,baseball games, football games, bicycle races, and swimming races. Bynetworking two or more exercise machines, the users of the machines canparticipate in team sports at home or at the local health club.

In one aspect, the present invention relates to an exercise apparatuscomprising an exercise mechanism, a steering mechanism, a processor orcomputer, and a display system. During a workout, the user manipulatesthe exercise mechanism and the steering mechanism to freely navigatethrough an interactive simulated environment generated by the processorand displayed to the user by the display system. The processor monitorsthe exercise mechanism and the steering mechanism to determine userposition in the simulated environment. The processor also controlsdifficulty of the workout by varying the resistance of the exercisemechanism to simulate characteristics (e.g., topography, terrain, etc.)of the environment. The display is updated by the processor to provide acontinuous visual display of the user's position as the user navigatessubstantially unrestricted through the simulated environment.

In some embodiments, the exercise mechanism includes pedals and the usersits on a bicycle-type device to achieve exercise by pedaling. In theseembodiments, the steering mechanism is a handle located in front of theuser or preferably a pair of handles located on either side of the user.The bicycle-type device on which the user sits in order to exercisepreferably tilts and more preferably is capable of moving along any orall of the six degrees of freedom. The movement preferably is related tothe user's manipulation of the steering mechanism. The bicycle-typedevice can have one or more speakers built thereinto or attachedthereto. For example, the speaker(s) can be built onto or attached to aseat of the bicycle. In one preferred embodiment, the user pedals whilein the recumbent position (i.e., the bicycle-type device is a recumbentbicycle).

A recumbent bicycle provides a number of advantages over an uprightbicycle. For instance, for users having different heights, eye locationvaries less on a recumbent bicycle than on an upright bicycle. Thissmaller eye-level variation for a recumbent bicycle as compared to anupright bicycle means that, when the display system is one or moreviewing screens or monitors placed in front of the user, the recumbentbicycle provides a more comfortable viewing position for a broader userheight range for a given monitor and seat position as compared to anupright bicycle. This particular advantage stems from the fact that eyeheight tracks user height for an upright bike, but it varies with thelength of the user's trunk, neck, and head for a recumbent bike, andthis latter variation is typically much less (e.g., about half) than thevariation in user height. Also, as compared to an upright bike, mostpeople find a recumbent bike easier to mount and dismount as well asgenerally more comfortable to ride. People who most need exercise to getinto shape and/or lose weight typically are less intimidated by, andtherefore more likely to ride, a recumbent bike than an upright bikebecause recumbent bikes do not "expose" such people as much as uprightbikes. Another advantage a recumbent bike has over an upright bike isthat it is easier for a user to move (e.g., tilt) a recumbent bikebecause it is lower to the ground and thus has a lower moment ofinertia.

In some other embodiments, the exercise mechanism includes the pedals orsteps of a stair climbing exercise machine, and the steering mechanismis a handle (e.g., a T-bar-shaped handle) located in front of the user.The stair climber can be designed to move, and the movement preferablyis related to the user's manipulation of the steering mechanism. Themovement can include movements along any or all of the six degrees offreedom.

Unlike most known stair climbing simulators which use stairs or pedalsthat drop towards the ground at a fixed speed (either machine-set ormanually adjustable) regardless of the speed at which the user isclimbing/exercising, the invention may involve automatic adjustment ofthe speed of the steps based on the user's climbing/exercising speed.The automatic adjustment is performed in order to keep the user at aparticular height or distance above the ground. Some users associatethat distance with the quality or effectiveness of the workout. Thesteps are monitored and controlled to provide the proper resistance tokeep the exercising user at one of a plurality of possibleuser-selectable or computer-set (based upon interactions within thevirtual world) heights above the ground. Thus, the user canclimb/exercise at any speed he or she desires, and the user's heightabove the ground is automatically maintained at the user-selected value.

The processor or computer generates the interactive simulatedenvironment and monitors user manipulation of the exercise mechanism andthe steering mechanism to determine the user's position within theenvironment. The processor is configured to allow the user to travelsubstantially unrestricted throughout the environment by manipulatingthe exercise and steering mechanisms, to modify his or her course in theenvironment, and to participate in user-selectable activities within theenvironment. The processor is capable of running many different programsto provide a variety of simulated environments. Some programs provideroads, terrain, and obstacles for the user and the user's competition.The user can travel across roads and trails or choose to travel acrossgrass, water, or other more challenging terrain. Other programs mayprovide new worlds for the user to explore or even allow the user totravel across the solar system. Each program provides a simulatedenvironment, and in some preferred embodiments the environment ismulti-dimensional (e.g., three-dimensional) to appear more realistic.The user views the simulated environment or world through the displaysystem.

In some preferred embodiments, the processor provides feedback to theuser in response to the user's actions within the simulated environment.This includes not only visual feedback via the display system butpreferably also sound feedback via the speakers and interactivefeedback. Interactive feedback as used herein means modifying theresistance or speed of the exercise mechanism (e.g., the pedals of thebike, the steps of the stair climber, etc.) in response to the user'sactions in the simulated environment to simulate collisions and"drafting" situations. Drafting is defined to cover mainly thesituations when a user gets behind a moving object (e.g., another userin a networked situation, a computer-generated agent, etc.) and ispulled along to some extent such that the user no longer needs to exertas much energy to maintain the same speed. This may be done in bikeriding simulations. Interactive feedback is provided in both networkedand non-networked embodiments of the invention. In a networkedarrangement, the two or more participants in the simulated world canexperience interactive feedback based on interactions in the simulatedworld with each other or with other objects in the world. An example ofinteractive feedback is when a user collides with an obstacle or acompetitor in the simulated environment and "crashes" as a result, andthe processor then causes visual and audio feedback to the user (e.g.,showing the wreck on the display system and causing a correspondingcrashing sound to be projected by the speakers) as well as causing thepedals to chatter, stiffen, and/or lock-up or loosen. Collisions betweenobjects can either accelerate or decelerate the objects in the simulatedenvironment. In a head-on collision or a collision with a stationaryobject, the user would be decelerated and as a bike would feel the pedalresistance increase. However, if the user is hit from the rear byanother object, he would accelerate and feel a decrease in pedalresistance.

The processor, in some preferred embodiments, provides "tour guides" or"computer-generated agents" in the simulated environment. These entitiesreact to the user's position and movement within the virtual world. Theycan, for example, lead the user along a particular route within thesimulated environment and adjust speed to maintain a small lead on theuser thereby providing the user with a target to chase or follow. Theprocessor determines the user's actions in the environment and causesthe agents to react to these actions. This can help to motivate the userto exercise harder and to explore areas of the simulated environmentthat the user might not otherwise encounter. In general, the agents donot force the user to take certain actions within the environment butinstead entice the user to take certain actions.

The display system can be spaced from the user. For example, in someembodiments it is a viewing screen or monitor located in front of theuser or a plurality of monitors located in front of and/or partially orcompletely around the user. Alternatively, the display system can belocated closer or attached to the user. For example, in some embodimentsthe display system is a head-mounted device worn by the user.

In another aspect of the invention, the exercise apparatus isnetworkable with one or more other such exercise apparatus. When two ormore of these exercise apparatus are interconnected, they cancommunicate and exchange information to allow the users to engage insimulated sporting events as teammates or competitors.

Other objects, aspects, features, and advantages of the invention willbecome apparent from the following description and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like reference characters generally refer to the sameparts throughout the different views. Also, the drawings are notnecessarily to scale, emphasis instead being placed on illustrating theprinciples of the invention.

FIG. 1 is a block diagram of an interactive exercise apparatusillustrating the principles of the present invention.

FIG. 2A is a side view of an interactive exercise cycle of the presentinvention.

FIG. 2B is a top view of an alternative interactive exercise cycle whichincludes a plurality of visual display units.

FIG. 2C is a perspective view of one embodiment of a head-mounteddisplay to be worn by a user of an interactive exercise apparatusaccording to the invention.

FIG. 3 is a flow chart illustrating one process for determining a user'sposition as the user freely navigates through a simulated environment.

FIG. 4 is a partial perspective view of the interactive exercise cycleof FIG. 2A illustrating a frame movably mounted on a stationary base.

FIG. 5A is an exploded partially cut-away view of FIG. 4 illustrating amechanical linkage connecting the steering mechanism to the base.

FIG. 5B is a diagram of a single spring mechanical tilting arrangementshowing the seat in a tilted-left position, a center position, and atilted-right position.

FIG. 6 is a cross-section view of a pedal resistance device used in theinteractive exercise cycle of FIG. 2A.

FIG. 7 is a block diagram of an exercise apparatus-to-exercise apparatusnetwork according to the invention.

FIG. 8 is a block diagram of a network in which a hub controlscommunications between two or more exercise apparatus ("nodes") byreceiving information. from all nodes and directing information to allof, or to a subset of all of, the nodes.

FIG. 9 is a block diagram of a network in which a hub receivesinformation from all network nodes and broadcasts information to allnodes.

FIG. 10 is a block diagram of the interactive exercise apparatus of FIG.1 with a network interface.

FIG. 11 is a flow chart, similar to the flow chart of FIG. 3, whichillustrates a process for determining a user's position as the userfreely navigates through a simulated environment.

FIG. 12 is a block diagram of the hub of FIG. 8 or FIG. 9.

FIG. 13 is a flow chart illustrating a process for message processing inthe hub of FIG. 8 or FIG. 9.

FIG. 14A is a side view of an interactive stair climbing simulatorexercise apparatus according to the invention with some of the internalcomponents shown in dotted lines.

FIG. 14B is a more detailed diagram of some of the internal componentsshown in FIG. 14A.

FIG. 15 is a top perspective view of an interactive stair climbingsimulator exercise apparatus in which the steps and the handle move incorrespondence to the user's manipulations thereof.

FIG. 16 is a block diagram of a position controller for use with avirtual climber according to the invention.

DESCRIPTION

The present invention is generally directed to interactive exerciseequipment which engages a user's mind and body. The equipment can beprovided in the form of, for example, a "virtual bicycle" or a "virtualstair climber". Each of these two embodiments of the. invention arediscussed in detail below.

Referring to FIG. 1, an exercise device 10 comprises a support structure12 for supporting a user. The support structure 12 may include a bicycleseat or bucket seat. An exercise mechanism 14 for providing aerobicexercise to a user, such as cycling pedals, is disposed proximate thesupport structure 12. A steering mechanism 16, such as handles orhandlebars, is also positioned near the support structure 12.

An interactive simulated environment is generated by a processor 18,such as a computer, and displayed on a display system 20. The displaysystem comprises a viewing screen or multiple viewing screens to providea wider field of view. Alternatively, the display system is ahead-mounted display device 21 having a helmet portion 17, a viewingscreen portion 19, and a cable for coupling to the computer, as shown inFIG. 2C. One or more speakers 15 are coupled to the computer 18 forbroadcasting sounds such as sounds corresponding to the simulatedenvironment and/or the user's actions within the environment.

The user manipulates the exercise mechanism 14 and/or the steeringmechanism 16 to travel substantially unrestricted throughout theenvironment displayed on the display. To accomplish this, the processor18 monitors the exercise mechanism 14 and the steering mechanism 16 todetermine user position in the simulated environment. The processor 18controls the level of difficulty of the exercise mechanism 14 tosimulate characteristics (e.g., topography, terrain, etc.) of theenvironment. The display 20 is periodically updated by the computer 18to provide a continuous visual display of the user's position as theuser travels substantially unrestricted in the simulated environment.

In one embodiment, the invention is directed to an exercise cyclingapparatus as shown in FIG. 2A. The apparatus 22 includes a frame 24movably mounted to a stationary base 26. A bucket seat 25 is mounted tothe frame 24. The seat 25 enables a user to be seated in the recumbentposition which provides several biomechanical and aerobic advantages.Recumbent cycling has many advantages, some of which are listed above inthe Summary of the Invention section. Recumbent cycling engages thegluteus maximus, the largest muscle group, to provide for maximumaerobic activity before reaching the anaerobic threshold. The bucketseat 25 makes the recumbent position very comfortable for long rides. Inaddition, the recumbent position is less intimidating to overweightusers. The present invention, however, can employ the more commonupright exercise bicycle frame and seat without departing from the scopeof the invention.

A pair of cycling pedals 27 extend from a pedal resistance device 28.The pedal resistance device 28 is adjustable so that the pedals 27 canalways be within reach of a short or long-legged user. A user exercisesby manipulating the pedals 27. Two vertically oriented handles 30 arecoupled by a mechanical linkage 72 (see FIG. 5) to the frame 24 forsteering the cycle 22. The handles 30 are positioned so that one handleis located on each side the seat 25. As the user manipulates the handles30, the mechanical linkage cause tilting of the frame 24 relative to thebase 26. This feature simulates the turning action of a bicycle and isexplained in detail below.

A computer 32 capable of generating an interactive simulated environmentis mounted to an L-shaped leg 36 which extends from the stationary base26. The computer 32 can be powered by many different types ofmicroprocessors. One embodiment of the invention includes a personalcomputer based on the Intel 486 microprocessor. Other computers, such asthose based on the Motorola 68040 processor can be used. Regardless ofthe type of microprocessor employed, the computer typically alsoincludes one or more electronic storage devices for storing one or moredatabases which describe the simulated environment(s). The storagedevices can include CD-ROMs, hard disk drives, floppy disk drives, readonly memories (ROMs), or random access memories (RAMs). At run time, themicroprocessor reads the appropriate data from the database andconstructs the desired simulated environment.

A viewing screen, such as a television monitor 35, is positionedopposite the seat 25 and oriented to be viewed by a seated user. Themonitor 35 may be capable of showing computer generated graphics as wellas standard TV and VCR images. The monitor 35 is connected to thecomputer 32 to provide a visual (and optional audio) display of thesimulated environment. While the monitor 35 can be any size, a largermonitor is preferred. A variable speed fan 38 is mounted adjacent to themonitor 35. The computer 32 regulates the speed of the fan 38 to providean air flow which simulates wind speed. The speaker(s) 15 can be locatedin the monitor 35 or, more preferably, attached to the seat 25 (FIG.2B).

Referring to FIG. 2B, a central viewing monitor 44 and two side monitors46 can be employed. The two side monitors 46 provide peripheral visionwhich enhances the user's sense of motion. The side monitors may also beemployed for biomechanical data and/or status displays.

Referring back to FIG. 2A, a user operates the apparatus 22 by pedalingthe cycling pedals 27 and steering with the handles 30 to freelynavigate through the simulated environment. The computer 32 can vary thepedal resistance felt by the user by controlling the pedal resistancedevice 28. The computer 32 monitors pedal speed and steering directionto determine the user's position in the simulated environment. Based onthe user's action, the computer 32 provides the monitor 35 with updatedviews of the simulated environment which corresponds to the user'sposition. The monitor 35 provides the user with an ongoing visualdisplay of the simulated environment based on the user's positiontherein as the user freely navigates in the environment.

The computer 32 is capable of running many different interactiveprograms to provide a variety of environments. Some programs provideroads, terrain, and obstacles for the user. Other programs includeunderwater adventure, pedal powered flight simulators, and space travel.Each program provides a simulated environment which the user viewsthrough the monitor 35. The user freely navigates in the environmentusing the pedals 27 and the steering handles 30. In other words, usertravel in the simulated environment is substantially unrestricted. Thus,the user can travel across roads and trails or chose to travel acrossgrass and water as well as other more challenging terrain.

To satisfy a wide range of exercisers and to make for broad range ofexperiences the preferred simulated environments contain a plurality ofactivities which the user may spontaneously select as they tour theenvironment. For example, in a simulated Caribbean island, the users canfollow one or more tour guides around the island, they can enter a roadrally with computer-generated competitors, they can plunge into thewater and chase fish, or even search for the mysterious white whale.Other events include jumping from cliffs, and running jeeps off theroad.

Regardless of whether the invention is provided in the form of a virtualbike or a virtual stair climbing simulator, in some preferredembodiments of the invention, the computer provides feedback to the userin response to the user's actions within the simulated environment. Thisincludes not only visual feedback via the display system but preferablyalso sound feedback via the speaker(s) and interactive feedback (asdefined previously). Interactive feedback is accomplished by thecomputer interrupting the exercise mechanism (e.g., the pedals of thebike, the steps of the stair climber, etc.) as a result of collisions ordrafting in the simulated world. For example, if the user collides withan obstacle or a competitor in the simulated environment and "crashes"as a result, the computer causes visual and audio feedback to the user(e.g., showing the wreck on the display system and causing acorresponding crashing sound to be projected by the speakers) as well ascausing the pedals to chatter, stiffen, and/or lock-up or loosen.

Also, the processor, in some preferred embodiments, provides "tourguides" or "computer-generated agents" in the simulated environment.These entities react to the user's position and movement within thevirtual world. They can, for example, lead the user along a particularroute within the simulated environment and adjust speed to maintain asmall lead on the user thereby providing the user with a target to chaseor follow. The processor determines the user's actions in theenvironment and causes the agents to react to these actions. Theseagents elicit exercise from the user, and motivate the user to exerciseharder and explore areas of the simulated environment that the usermight not otherwise encounter. In general, the agents do not force theuser to take certain actions within the environment but instead enticethe user to take certain actions. Further details of these entities areprovided below.

One or more of the computer-generated agents or entities can be movingabout in the environment at any given time. In a cycling environment,these entities or actors may be depicted as other cyclists, cars,trucks, or even animals. The motion and behavior of the actors isconsistent with the user's expectations. For example, trucks drive onroads, bikes can follow paths or go cross country but cannot fly. Theseactors generally obey the physical laws of the particular simulation inwhich they exist, react to the user's actions in the environment, andmotivate the user to exercise harder. Another example is a deliverytruck entity which is programmed to avoid hitting objects especiallypeople such as cyclists. This can be fun for the user as he or shecrosses the path of the truck and then watches as the truck attempts toavoid a collision by swerving out of the way. If the truck is unable toavoid a collision with the cyclist, the user will feel a jolt in thepedals (the interactive feedback) during the collision with the truck.Interactions with the truck motivate the user to pedal fast to catch thetruck and get in its way.

In a networked simulation (networking is describe. below), the motionsof these actors can be communicated across the network. In this manner,two real exercisers who are sharing a virtual environment can interactwith the same actors. For example, two virtual bikes could leave thetruck driver no option but to swerve off the road into a lake. Whilethis is not something that cyclists would do in the real world, it canbe a humorous and entertaining event in a virtual world.

Many existing exercise machines and video games have a start-up sequencewhich requires a user to enter certain facts, such as weight, skilllevel, desired course and length of workout. The information is usuallygathered through a set of buttons with LED indicators. However, thistype of interrogation can be confusing and time-consuming. Accordingly,the cycling apparatus 22 (as well as the stair climbing simulatordescribed below) may gather some of this type of information indirectly.For example, a sensing device (69 in FIG. 5) can be incorporated intothe seat 25 for automatically weighing a user. Other information may begathered by means of the user navigating down the path of choice. Forexample, a person who desires a tough workout could head for a hillypath, and this choice would be an input to the computer regarding thetype of workout desired by the user. Other choices may be made beresponding to various road signs or other markers in the simulatedenvironment. By using this navigational metaphor, the user is able tomake choices in a natural and intuitive manner. If the user misses achoice he or she can simply turn around. A user exercising with a stairclimbing simulator according to the invention can enter, for example, adesired above-ground distance in this intuitive manner. In general, anyinformation about the user and/or the type of workout desired by theuser can be automatically gathered in this manner which does not requirethe user to be directly asked or to directly answer any questions.

The computer 32 may be adapted to participate in a communication networkconnecting several exercise devices. As such, multiple users canexercise in the same simulated environment. This feature stimulatesimpromptu races and competition among users. By allowing users tonavigate freely around the same environment, they can engage in friendlytouring or fierce competition on a spur of the moment basis. Thisnetwork feature is described in more detail below with reference toFIGS. 7-13.

A general process flow sequence of the interactive software within thecomputer 32 is shown in FIG. 3. Once a particular environment has beenselected, the computer monitors a variety of parameters including userweight 48, pedal speed 50, and steering/movement 52 (step 54). Thecomputer uses these parameters to update the user's position anddirection in the environment (step 56). The computer preferably alsoupdates the position and actions of the agents working in the simulatedenvironment, which position and actions preferably depend upon theuser's activity. Subsequently, the computer generates a visual (andoptionally audio) image of the environment based on the updated positionof the user (step 62). The computer preferably also provides the agentsdescribed previously. The monitor 35 displays updated images at least 7times/second. The computer 32 updates pedal resistance to simulate suchelements as hills, gear changes, road surfaces, simulated headwinds, anddrafting of opponents (step 60). The computer preferably also providesthe interactive feedback described previously. The fan speed can bemodulated to correspond to the simulated windspeed and speed of travel.Finally, the computer 32 may also generate general sounds such asbackground music. One or more speakers for projecting the sound can belocated in/on the computer, in/on the display(s), or elsewhere in/on theexercise machine (e.g., in/on the seat near the user's head). (FIG. 2Bshows two speakers attached to the recumbent seat 25, and a microphoneand a speaker are shown and described below with reference to FIG. 10.)

A detailed illustration of the seating portion of the exercise apparatus22 is provided in FIG. 4. The seat 25 upon which the user sits ismounted onto the frame 24. The frame 24 is movably mounted to thestationary base 26 by hinges 64. Although only one hinge 64 is shown, itis noted that one or more hinges are used. Push button controls can beprovided on the handles 30 for shifting gears and other interactivefunctions. These buttons preferably are at the end of the handles 30such that they can be depressed with the user's thumbs. The buttons arecovered by one-piece elastomeric hand grips which protect the buttonsfrom the user's sweat. A handle 65 preferably is provided which iseasily reachable by the user sitting in the seat 25. The handle 65 isused to adjust for the height of the user. If the user needs to adjustthe system to fit his height, the user manipulates the handle to releasethe pedal mechanism 27/28 (FIG. 2A) and then moves the pedals away ortowards him or her (as indicated by an arrow 66 in FIG. 2A) to thedesired position. The seat 25 preferably is in a fixed position, and itis the pedals which are adjusted back or forth to suit the user.

Referring to FIG. 5A, a mechanical linkage 72 allows the frame 24 totilt relative to the base (e.g., up to 15 degrees or more to either sideof the longitudinal vertical plane) in response to manipulation of thehandles 30 for simulating the turning action of a bicycle. The handles30 are connected to the mechanical linkage 72 by a beam 68. Themechanical linkage 72 includes a horizontal beam 70 positioned between apair of vertical posts 71. The posts 71 extend from the stationary base26. The mechanical linkage also includes bearings 73 mounted in theframe 24 and holding a pivoting vertical post 74.

As the user manipulates the handles 30 back and forth (as indicated bythe arrows) to steer in the simulated environment, the beam 68 turnscausing the vertical and horizontal posts (74, 70) to move in the samedirection laterally. The horizontal post 70 contacts the vertical post71 which pushes the frame 24 in the opposite direction. This causesframe 24 to tilt about the hinge 64 causing the seat 25 and the pedals27 to tilt accordingly.

A pair of springs 75 are positioned on opposite sides of the seat 25.The springs 75 are disposed between the frame 24 and the base 26 forcentering the frame 24 once the user lets up on the handles 30 or getsoff the seat 25. As such, the springs 75 serve as a self-centeringmechanism to ensure that the seat 25 is vertically aligned for easymounting and dismounting.

A sensing device 69 located under the seat 25 measures the user's weightand adjusts the stiffness of the self-centering springs 75. The springs75 are adjusted to stiffer settings for heavier persons and less stiffsettings for lighter persons. As such, each user can experience the fullrange of tilting motion.

Additional sensors may be employed in and around the seat 25 tonon-invasively monitor, for example, the user's heart rate, pedal speed,and power output. For example, the sensing device 69 provides anestimate of the user's body weight. These inputs are used by thecomputer software to determine the caloric output of the user.

Referring to FIG. 5B, in an alternative embodiment to that shown in FIG.5A, tilting is accomplished with a different mechanical set-up. Thisalternative arrangement utilizes only one spring 200. The frame 24 andthe seat 25 move together relative to the stationary base 26 in responseto manipulation of the handles 30 for simulating the turning action of abicycle. The handles 30 are not shown in FIG. 5B for simplicity andclarity. This mechanical arrangement includes two pulleys 202, 204 andtwo cables 206, 208 coupled to the spring 200. With the seat in theuntilted center position, both cables have approximately equal tension.As the user manipulates the handles 30 back and forth to steer in thesimulated environment, the seat and the frame tilt together and one ofthe two cables is pulled such that it compresses the spring 200 whilethe other cable goes loose. For example, in tilting to the right, cable206 pulls up on a hook which compresses the spring 200, and in tiltingleft, cable 208 pulls up on the hook compressing the spring 200. Thespring 200 is pre-loaded to pull down on the hook and bring theseat/frame to the center position once the user lets up on the handlesor gets off of the seat. Thus, this alternative embodiment also has aself-centering mechanism to ensure that the seat is vertically alignedfor easy mounting and dismounting. As with the embodiment of FIG. 5A,the frame, seat, and pedals tilt together with this single springarrangement of FIG. 5B. Also, a sensing device can be located under theseat to measure the user's weight and adjust the stiffness of theself-centering spring 200. The spring 200 is adjusted to stiffersettings for heavier persons and less stiff settings for lighterpersons. As such, each user can experience the full range of tiltingmotion as with the embodiment of FIG. 5A. Additional sensors may beemployed in and around the seat to monitor non-invasively, for example,the user's heart rate, pedal speed, and power output. These inputs canbe used by the computer to determine, for example, the caloric output ofthe user.

Referring back to FIG. 4, the seat, frame, and pedals of a virtual bikeaccording to the invention can, in response to the user's manipulationsof the handles, move at least in a side-to-side tilting action asdescribed above and as indicated by an arrow 210 in FIG. 4. Movement ofthe seat, frame, and pedals also preferably is allowed via manipulationof the handles in the straight-back and straight-forward directionsindicated by an arrow 212 and in the tilting back and forth directionsas indicated by an arrow 214. Thus, user manipulation of the handlescauses movement of the seat and the pedals preferably in any of sixdegrees of freedom.

The apparatus of the present invention can employ a traditionalfreewheel and flywheel to provide pedaling resistance. However, a closedloop digital control system may be employed instead. As such, pedalingresistance would be provided by a simpler drive mechanism controlledelectronically by a digital control system to provide for smoothpedaling strokes.

Referring to FIG. 6, the cycling pedals 27 are connected to the pedalresistance device 28. The device 28 is adjustable (via the handle 65 ofFIG. 4) to accommodate users having short and long legs. The pedals 27turn an axle 77. The axle 77 is coupled to a braking device 79 by aplurality of belts 76 and pulleys 78. The braking device 79 can includeany of the following mechanisms: a magnetic particle brake, hysteresisbrake, mechanical straps and pads, electrical generators, torque motorsor magnetic inductance. In one embodiment, a hysteresis brake is used(such as Model HB produced by Magtrol, Inc. of Buffalo, N.Y.) providinga small simple means of providing the resistance to the pedals.

The digital control system 82 is connected to the brake 79 by wires 80.Responsive software in active software in the computer 32, the controlsystem 82 controls the pedal resistance of the braking device 79electronically, thereby emulating the traditional flywheel/freewheelarrangement to provide the proper combination of pedal resistance andinertia for smooth pedaling revolutions. For example, an extremely lightresistance is provided to simulate downhill travel and higher resistanceis provided to simulate gear changes, wind resistance, and hills. Thepedals can be driven backwards to reverse direction.

As mentioned previously with reference to FIG. 3, the computer (18 inFIG. 1, 32 in FIG. 2A) can be interconnected with computers of one ormore other exercise apparatus via a network interface module. With twoor more of these exercise apparatus networked together, the computerscan communicate and share information and allow the users to navigatefreely in the same simulated environment and to interact as teammates orcompetitors.

Referring to FIG. 7, a computer of a first exercise apparatus 90 isinterconnected to a computer of a second exercise apparatus 92 via atwo-way communication link 94. While only two exercise apparatus areshown in FIG. 7, it is possible to network more than two such machinestogether via the link 94. Note that while each exercise apparatus 90, 92can be a device in accordance with the previous description whichreferences FIGS. 1-6, each also can be any other type of exercisemachine which: (i) allows a user to exercise some part of her (or his)body; (ii) allows a user to indicate a desired direction of motion(i.e., steer); and (iii) includes a computer or processor to allowinterconnection and communication with other such exercise machines. Forexample, each exercise apparatus can be a stair climbing simulator whichis described below. Also, one networked apparatus can be a virtual bikewhile another can be a virtual stair climber. In one embodiment, one (ormore) of the networked exercise machines is a stair climber machinehaving a pipe or handle which the user pushes and/or pulls (e.g., withhis or her hands) in various directions to indicate various desireddirections of motion, the machine having one or more transducersattached to the handle such that the user's manipulations of the handleare converted into signals the machine's computer can understand and/orprocess.

Computer-generated agents and other moving objects can also be sharedacross the network so that behavior of the agents in the simulatedenvironment is consistent on all of the networked exercise apparatus.For example, two exercisers could be chasing the same whale in anunderwater adventure and the whale would react to both users in aconsistent fashion. The modeling of the networked agents can beaccomplished using methods known as distributed simulation technology.This technology was originally developed for use in military simulatorssuch as the SIMNET system. One implementation of distributed simulationtechnology assigns one of the networked machines as the "master" for aparticular agent and other machines are designated as "ghosts". Eachmachine updates the actions of its agent (master or ghost) according tothe program and interactions with various users. Periodically, typicallyonce every few seconds, the master program transmits an informationpacket over the network to synchronize the state of the ghost agents. Inbetween synchronization events, both the master and ghosts areresponding to similar inputs and therefore their behaviors tend to besimilar over that short time span. The periodic synchronization packetskeep the state of the agents on different machines from diverging overtime. This method accomplishes the goal of keeping the behavior of theagents similar across the network with a minimum of communication. Othermethods for distributed simulation could also be employed.

The link 94 can be any type of two-way transmission channel such astelephone lines (analog and/or digital) or direct-connecting cables. Thelink 94 also can be free space in the case of communication byelectromagnetic wave transmission and reception. The physical distancebetween the first and second exercise apparatus 90, 92 can be a factorin determining the type of channel to employ for the link 94. Forinstance, if the two apparatus 90, 92 are located physically near eachother (e.g., in the same building), the link 94 can be a coaxial orelectrical cable. As another example, if the two apparatus 90, 92 arelocated physically away from each other (e.g., in different cities butin the same state), the link 94 can be established by telephone lines.The link 94 also can, in some embodiments, represent generally acomputer network (e.g., a token ring network, an Ethernet network, etc.)on which two or more exercise apparatus exchange information.

Regardless of the physical distance between the two (or more) networkedexercise apparatus, the network connection allows the users to exercisein the same simulated environment. The computer in each exerciseapparatus (not shown in FIG. 7) controls the communications betweenapparatus. The computers exchange various parameters (such as userweight 48, pedal speed 50, and steering/tilt 52 as indicated in FIG. 3)so that each computer can display to its user the position and directionof the other users in the environment. In general, the communicationsbetween the networked computers allow each user to interact with theother users.

In the simulated environment, each user can be depicted with a unique(three-dimensional) icon, picture, or other symbol. During thesimulation, the same environment database is stored and executed on eachmachine. Each computer is responsible for updating the environment sothat its user sees herself (or himself) in relation to all othernetworked users. The desired simulation typically is selected byagreement of all interested users on the network prior to the start ofthe group simulation. After selection, that environment's database istransferred between computers (over the link 94) so that each computercan execute the same environment and participate in the groupsimulation. Typically, each computer has a permanent copy of theselected simulation environment stored therein and thus does not need toreceive it over the link 94. Mechanisms to allow networked users to joinan already-begun group simulation can be provided.

In addition to sharing position, direction, etc. parameters, thenetworked computers can share voice information. While a microphone isnot shown in FIG. 7, it should be understood that a microphone can beelectrically coupled to the computer and located in/on the computer,in/on the display(s), or elsewhere in/on the exercise machine (e.g.,in/on the seat near the user's head). (A microphone and a speaker areshown in FIG. 10 and described below with reference to that drawing.) Ifthe link 94 is established with telephone lines, the phone signal can bemultiplexed to allow for both voice and data communication between theusers. This dual use of the phone signal is possible due to therelatively low-bandwidth of communication required for the sharedparameters (e.g., position, direction). By allowing voice communication,the users can talk in real-time while, for example, racing pedal-poweredchariots though ancient Rome.

The communication interconnections described above with reference toFIG. 7 can be referred to as "local networking" or "person-to-personnetworking" in that each computer of each exercise apparatus on thenetwork can communicate directly with any other computer of any otherexercise apparatus on the network. In contrast to the network of FIG. 7is the "large-scale direct network" of FIG. 8 in which two or moreexercise apparatus (four are shown in the disclosed embodiment, namely96, 98, 100, 102) communicate through a central hub processor 104. Eachexercise apparatus 96, 98, 100, 102 is coupled to the hub 104 by atwo-way communication link 106, 108, 110, 112 which each can be any of avariety of two-way links as described above with reference to FIG. 7.The hub 104 is responsible for limiting the information directed to eachapparatus in the large-scale direct network of FIG. 8. The hub 104 canensure, for example, that each apparatus only gets (parameter) updatesabout other users in the same general area of the simulated environment.

Referring to FIG. 9, a "large-scale broadcast network" is shown which issimilar to the network of FIG. 8 except that the large-scale broadcastnetwork of FIG. 9 includes two or more exercise apparatus (four areshown) which each (i) send information to the central hub processor 104over a low-bandwidth line 114, 116, 118, 120 and (ii) receive broadcastsfrom the hub 104 over a high-bandwidth line 122. Although thelow-bandwidth lines are used primarily to send information to thecentral hub processor, one or more of these lines can be bi-directionallines such as telephone lines. An exercise apparatus connected to thecentral hub processor by a bi-directional line can receive informationfrom both its high-bandwidth and low-bandwidth lines. In one disclosedembodiment, the high-bandwidth line 122 is a cable TV channel and thelow-bandwidth lines 114, 116, 118, 120 are telephone lines orinteractive cable TV lines.

In the large-scale broadcast network configuration of FIG. 9, eachexercise apparatus 96, 98, 100, 102 listens to all data broadcast by thehub 104 but generally pays attention only to that data which has abearing on it. The hub 104 preferably groups messages by regions of thesimulated environment to facilitate this selective receipt of broadcastdata by the exercise apparatus 96, 98, 100, 102. For instance, when thehub receives data transmitted from the user's computer over thelow-bandwidth channel, the hub receives the data from all of theconcurrent users, processes it in real-time to resolve all collisionsand conflicts, groups users in a specific region of the simulatedenvironment into the same group, and then broadcasts the groupedinformation (e.g., updated position information) over the high-bandwidthchannel. The computers in a particular group only listen to informationabout their group, and they only display information about users in thesame general area (i.e., in the same group).

The high-bandwidth channel of FIG. 9 can be used to broadcast thecontent of the simulation environment database to everyone on thenetwork. If a cable TV channel is employed as the high-bandwidthchannel, an entire simulation database can be broadcast in about one tothree seconds. By continuously broadcasting one environment afteranother over a cable TV channel, a hub could provide from 50 to 100choices, for example, to connected users with virtually no waiting.

Regardless of whether the network is configured as in FIG. 7, FIG. 8, orFIG. 9, the users on the network can be provided with a variety ofsimulation environment selections (e.g., by menus displayed to them). Awide range of exercise environments could be offered such asenvironments geared towards competition, education, or the future. Inaddition, the network could allow users to customize their own virtualenvironments. This could be done by providing each computer withsoftware capable of modifying existing environments or capable ofbuilding new environments from a set of fundamental "blocks" provided tothe user. These custom environments could then be shared with others onthe network. Also, the network could allow each user to select and/orcustomize her (or his) icon or symbol which all other users will see ontheir respective displays. Icon selection can be accomplished by: (i)the central hub presenting each user with a pre-set menu from which theuser selects his persona; (ii) the central hub allowing limited editingor customizing of the figures; (iii) software allowing users to buildtheir own icon on their respective computer; or (iv) distributingpackaged software with a set of pre-prepared persona.

For these networked systems, the sporting applications are tremendous.Races and events could be set-up to allow competition between usersphysically spread across the globe. In one scenario, a new raceenvironment is designed each week. During the week, users download thecourse and take training rides to learn the course and plan theirstrategy. While training they see other athletes and may engage inimpromptu competitions. The big race is at a predetermined time. All ofthose who are interested tune-in and commence an all-out race for thefinish. During the race you can jockey for position with other ridersand keep track of the leaders. The winners might earn prizes or go on tonational and international events. All without leaving your house orhealth club.

The action is not limited to racing or even competitive simulations.Team sports similar to soccer or football could be implemented as wellas scavenger hunts, capture the flag, and other adventure games.

Whether the network configuration is as shown in FIG. 7, FIG. 8, or FIG.9, the individual exercise apparatus which are interconnected will eachhave a network interface module of some sort which allows them tocommunicate. Referring to FIG. 10, the disclosed embodiment of theexercise apparatus 10 includes a network interface module 124 whichallows communication over a relatively low-bandwidth telephone lineand/or a relatively high-bandwidth cable TV line. The other componentsof the exercise apparatus 10 were described previously with reference toFIG. 1. Note that any of a variety of other types of exercise machinescan be used instead of the apparatus 10 as described previously withreference to FIG. 7.

The computer 18 communicates with the network interface module 124 asindicated by a double-headed arrow 126. The network interface module 124includes a telephone modem 128 for communication over relativelylow-bandwidth telephone lines, and it also includes a voice and datamultiplexer and demultiplexer 127 coupled to the modem 128. In thedisclosed embodiment, a microphone 121 and an audio mixer 123 areconnected to the voice/data mux/demux 127. Audio signals from thisvoice/data mux/demux 127 are mixed with audio generated by the computer18 and fed to one or more speakers 15. The network interface module 124also includes a cable TV interface for communication over relativelyhigh-bandwidth cable TV lines. The cable TV interface includes a cableTV decoder 130 (i.e., an analog-to-digital converter) and a memorybuffer 132.

A general process flow sequence of the interactive software whichexecutes on the computer of each networked exercise apparatus is shownin FIG. 11. FIG. 11 is similar to FIG. 3 except that FIG. 11 is directedto an apparatus which operates in the network configuration of FIG. 7,FIG. 8, or FIG. 9. Steps which the computer takes when networked toother computers are indicated generally by the numeral 134. When thecomputer is in a downloading mode 136, it is either (i) transmitting asimulation environment database to other computers or to the hub, or(ii) receiving a simulation environment database from other computers orfrom the hub. When the computer is in an interactive mode 138, it iseither (i) transmitting parameters relating to the position, direction,etc. of the user or other locally modeled agents, or (ii) receiving suchparameters on other users and agents in the group simulation from theirrespective computers or from the hub.

In the disclosed embodiment, the central hub processor of FIGS. 8 and 9includes an input processor 140 which receives data from the networkedexercise machines, as shown in FIG. 12. In general, the input processor140 includes one modem for each networked machines, and in thisdisclosed embodiment, each modem is a telephone modem for receivingsignals from the networked machines via the telephone lines. The hubalso includes an input data queue 142 which is fed by the inputprocessor 140. The queue 142 holds data for the processor 144 which canbe a microprocessor such as those manufactured and sold by Intel,Motorola, or any number of other suppliers. The remainder of FIG. 12shows two embodiments. The top data stream in FIG. 12 is directed to theembodiment in which the hub is used in the large-scale broadcast networkof FIG. 9. The bottom data stream in FIG. 12. is directed to theembodiment in which the hub is used in the large-scale direct network ofFIG. 8. Note that the hub can include the components in both the top andbottom data streams of FIG. 12 thereby allowing the same hub to be usedin either a direct or broadcast network. In both the broadcast networkand the direct network, the hub includes an output buffer 146, 148. Inthe broadcast network, the hub further includes an encoder 150 whichperforms digital-to-analog conversions so analog signals can bebroadcast over the cable TV channel. In the direct network, the hubfurther includes an output processor 152 which, like the input processor140, includes modems for sending signals to the networked machines viathe telephone lines.

A general process flow sequence of the processes performed by the hub ofFIG. 8 and the hub of FIG. 9 is shown in FIG. 13. At step 154, the hubof FIGS. 8 and 9 reads information from an incoming queue 156 (which maybe the input data queue 142 of FIG. 12 or a separate list built andmaintained by the processor 144 from data extracted from the queue 142)and determines at step 158 whether the incoming message is a request fora database or an update (e.g., of a particular networked user's oragent's position, direction, etc. in the simulated environment). If itis a request, the hub locates the requested database (step 160) bysearching an externally or internally maintained library of databases162. The located database is then broken into data packets and addressedto the appropriate user(s) (step 164) and the packets are added (step166) to an outgoing message queue 168. If it is an update, the hubrecords the new state of the user's or agent's icon/object (step 170) byreferencing an externally or internally maintained object database 172which contains the location, etc. data on all objects (i.e., users,agents, etc.) in the environment. The new state information is thenadded (step 174) to the outgoing message queue 168. Next, the hub takesmessages (step 176) from the outgoing message queue 168 and determineswhich group of users should receive the message (step 178) byreferencing the object database 172. The remaining steps the hubperforms depend on whether the hub is used in the large-scale directnetwork of FIG. 8 or the large-scale broadcast network of FIG. 9. If inthe large-scale direct network configuration, the hub addresses theoutgoing message to the individual networked machines which need toreceive the message (step 180). The message is then sent (step 182). Ifin the large-scale broadcast network configuration, the hub sorts theoutgoing messages into groups (step 184) and then broadcasts to allnetworked machines (step 186).

Referring to FIG. 14A, a virtual climber 250 according to the inventioncomprises a supporting frame 252, a pair of pedals or steps 254 coupledto a climbing apparatus within a housing 258, a movable handle 256 forsteering, and a display system 260. The computer also is located withinthe housing 258, and its purpose and functionality is the same as thatdescribed previously for the computer in the virtual bike. For instance,the computer of the virtual climber performs generally the samemonitoring, controlling, feedback (e.g., visual, sound, and/orinteractive), tour guides or agents functions, networking functions,etc. While the display system 260 is shown as a monitor, it is possiblefor it to be a head-mounted display or a plurality of monitors, as.shown and described previously for the virtual bike embodiment of theinvention. Below the monitor is a housing 262 into which the handlesextend and which contain steering apparatus. Part of the frame 252 is apair of stationary rails 264 which can be useful in mounting anddismounting the steps 254. These rails 264 can be optional. One or morespeakers preferably are located somewhere in or on the virtual climber250 (e.g., in the monitor).

A user of the virtual climber 250 manipulates the steps 254 and/or thehandle 256 to travel substantially unrestricted throughout theenvironment displayed on the display. To accomplish this, the processor18 monitors the user's manipulations of the steps 254 and the handlesteering mechanism 256 to determine user position in the simulatedenvironment. The handle is movable at least in one direction such asside-to-side (as indicated by an arrow 266) and preferably in any of sixdegrees of freedom, i.e., side-to-side (arrow 266), in and out (arrow268), and up and down (arrow 270). The computer controls the level ofdifficulty of the steps 254 (e.g., the speed of the climb) to simulatecharacteristics of the environment. The environment preferably is aninteractive simulated three-dimensional environment and more preferablyan interactive simulated three-dimensional fluid environment such as anunderwater environment or an in-air environment. For example, the usercan climb higher into the air the harder or faster he or she pedals orclimbs.

Referring to FIG. 15, in some preferred embodiments, the steps 254 andthe handle 256 move together in response to the user's manipulations ofthe handle and/or the steps. The movement is at least in. one directionsuch as side-to-side (arrow 272) as shown, and preferably is in any ofsix degrees of freedom such as side-to-side, in toward the display 260and back away from the display 260 (arrow 274), and up and down (intoand out of the page). If a user turns the handle left or right (arrow266 in FIG. 14A), the steps and handle move correspondingly left orright while the display 260 and supporting frame 252 remain stationary.In the disclosed embodiment, wheels 276 allow the side-to-side movement,and the steps, handle, and housing 258 all move together.

Unlike most known stair climbing simulators which use stairs or pedalsthat drop towards the ground at a fixed speed (either machine-set ormanually adjustable) regardless of the speed at which the user isclimbing/exercising, the virtual climber of the invention may alsoprovide automatic adjustment of the speed of the steps based on theuser's climbing/exercising speed and a user-selected orcomputer-selected (based on activities in the virtual world) height offof the ground. Referring to FIG. 14A, the automatic adjustment isperformed in order to keep the user at the desired height or distanceabove the ground, d. Some users associate that distance, d, with thequality or effectiveness of the workout. The computer monitors andcontrols the steps to provide the proper resistance to keep theexercising user at one of a plurality of user-selectable orcomputer-determined (based on activities in the virtual world) heightsabove the ground. The value of "d" can be input to the computer via theintuitive input method described previously. The user can climb/exerciseat any speed he or she desires, and the user's height above the groundis automatically maintained at substantially the user-selected value.

Referring to FIG. 16, a position controller 278 includes two digitalposition encoders 280, 282. One of the encoders 280 is associated withthe left stepper, and the other encoder 282 is associated with the otherstepper. The encoders are mounted on the stepper axles and are used totrack the position of the steps. The actual vertical position of theuser can be inferred from the stepper position by signal processing.methods. In the disclosed embodiment, the computer 284 in the housing258 processes the signals coming from the encoders 280, 282 to removethe oscillatory portion of the stepper position and determine the user'saverage actual vertical position. It is preferred to use a slidingaverage of the left and right stepper positions in which the average istaken over the period of one stepper stroke. Other methods of measuringthe user's vertical position can be used such as a retractable cord tiedto the user's belt. The computer 284 then compares this estimatedvertical position to the desired, user-selected distance, d (286), usinga proportional control law. This law is given by

    CS=G*(EVP-DVP)

where CS is the climbing speed, G is the gain, EVP is the estimatedvertical position, and DVP is the desired vertical position (i.e., d).If the comparison indicates that the user is above the distance "d", thecomputer 284 speeds up the rate at which the steps fall (i.e., decreasesthe resistance of the steps). This has the effect of lowering the usertoward the desired height "d" if the user maintains the same level ofexercise that resulted in his or her rise to the too-high height.Conversely, if the user has fallen too low (because he or she is notworking hard enough), the stepper resistance is decreased to allow theuser to rise higher while working at the same level. In the disclosedembodiment, the proportional controller uses a proportional control lawto determine the input to the stepper resistance system 288. Note thatthe signal processor and proportional controller functions can beperformed by hardware separate from the computer. The positioncontroller 278 thus automatically keeps the user at substantially thedesired height, d, regardless of how fast or slow the user is climbingor if the user alters his or her speed over the course of the workout.

Referring to FIG. 14A, the housing which contains the computer alsocontains the climbing apparatus, as indicated previously with referenceto the same drawing. The climbing apparatus is shown in more detail inFIG. 14B. Many different types of climbing mechanisms may be suitablesuch as the one described in U.S. Pat. No. 4,938,474 to Sweeney et al.

Other modifications and implementations will occur to those skilled inthe art without departing from the spirit and the scope of the inventionas claimed. Accordingly, the invention is to be defined not by thepreceding illustrative description but instead by the following claims.

What is claimed is:
 1. A stair climbing simulator exercise apparatus,comprising:a pair of steps which a user manipulates to achieve exercise;a steering mechanism disposed proximate the steps which the usermanipulates to indicate direction of motion; a computer for generating asimulated environment, for controlling the steps, for monitoring usermanipulation of the steps and the steering mechanism to determine userposition in the simulated environment, and for automatically adjustingthe steps to maintain the user at substantially a particular distanceabove the ground regardless of the speed at which the user manipulatesthe steps; and a display system coupled to the computer for providing avisual display of at least the user's position in the simulatedenvironment.
 2. The apparatus of claim 1 wherein the computer isconfigured to (i) enable the user to travel substantially unrestrictedthroughout the simulated environment by manipulating the steps and thesteering mechanism, (ii) determine updated user position in thesimulated environment, and (iii) enable the user to participate inuser-selectable activities within the simulated environment.
 3. Theapparatus of claim 1 wherein the computer includes a network interfaceto allow communication over a communication channel with at least oneother such exercise apparatus.
 4. The apparatus of claim 1 wherein thecomputer also provides interactive feedback to the user based on theuser's actions in the simulated environment.
 5. The apparatus of claim 1wherein the computer generates an interactive simulatedthree-dimensional environment.
 6. The apparatus of claim 1 wherein thecomputer generates an interactive simulated three-dimensional fluidenvironment.
 7. A stair climbing simulator exercise apparatus,comprising:a pair of steps which a user manipulates to achieve exercise;and means for automatically adjusting the steps to maintain the user atsubstantially a particular distance above the ground regardless of thespeed at which the user manipulates the steps.